Barrier Islands

Photo of a barrier island


Barrier spits and islands are long, narrow landforms off the coast of the United States that are separated from the mainland by bays or lagoons. They formed near the end of the last Ice Age, as the rising seas winnowed away the cliffs, headlands and river deltas along the coast and inundated previously dry areas.

Barriers are found along the Atlantic coast, the Gulf of Mexico coast, and in certain regions of the Alaskan coast. The presence of significant amounts of sediment, in concert with wave and current action and stable sea level, results in the formation of barriers in many coastal regions.


Reviewed 27 Sep 2016

Barrier Formation

Barrier formation
Source: National Park Service

Continental Shelf

The continent shelf is the zone bordering a continent that extends from the line of permanent immersion of the land to a depth where there is a steep descent into the deep ocean.